1. Field of the Invention
This invention relates to a curing apparatus for curing an uncured tire by using upper and lower and sector molds as well as a method for the manufacture of tires using the same.
2. Description of Related Art
As the conventional tire curing apparatus, there is known an apparatus described, for example, in JP-B-46-2705 1. This apparatus comprises a lower mold mainly forming a sidewall portion of a tire, an upper mold mainly forming another sidewall portion of the tire and capable of approaching to or separating away from the lower mold, a sector mold mainly forming a tread portion of the tire and comprised of plural arch-shaped segments arranged in a peripheral direction so as to show a ring form as a whole, and a tapering portion integrally united with the upper mold so as to approach to or separate away from the sector mold. When the tapering portion approaches to the sector mold, the arc-shaped segments are moved by a taper face formed in an inner periphery of the tapering portion toward the inside in a radial direction in synchronousness therewith to close them to each other. In this apparatus, a pin is fixed to a top end portion of an arm fastened to an outer end portion of each of the arc-shaped segments in the radial direction, while the pin is supported pivotably and movably in the radial direction to the lower mold and also a spring is disposed on the lower mold energizing the pin outward in the radial direction.
If it is intended to cure an uncured tire by using the above tire curing apparatus, after the uncured tire is placed on the lower mold, the upper mold and the tapering portion are approached to the sector mold and then arc-shaped shaped segments are moved by the taper face of the tapering portion in synchronousness therewith toward the inside in the radial direction against the spring. When these arc-shaped segments are moved to an inner limit in the radial direction, they are closed to each other to form a continuous ring shape. In this case, the upper and lower molds and the sector mold are closed to each other and the uncured tire is housed in the inside thereof. Thereafter, the inside of the molds is rendered into given high temperature and high pressure, whereby the uncured tire is cured. Next, when the upper mold and the tapering portion are separated away from the lower mold and the cured tire is raised, each of the arc-shaped segments and the arm are rocked upward around the pin by rocking means so as to be enlarged. At the same time, the arc-shaped segments are released from restraint with the tapering portion, so that they are moved to an outer limit in the radial direction by the energizing force of the spring. Then, the cured tire taken out from the mold is transported to subsequent step.
In the conventional tire curing apparatus, however, the arc-shaped segments are separated from the tread portion of the cured tire by rocking the arc-shaped segment and arm upward around he pin as mentioned above, so that a normal line to the cured tire and a normal line to the arc-shaped segment intersect at an obtuse angle in the separating point and hence the land portions of the cured tire are taken out from a dent portion of the arc-shaped segment while bending at the obtuse angle. As a result, there are caused some problems that it is difficult to conduct the operation of taking out the cured tire from the tire curing apparatus and the cut or flaw is created in the land portion. And also, the curing apparatus requires the use of the rocking means for rocking the arc-shaped segment and hence it becomes complicated in the structure and high in the cost.